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  <title>Document</title>
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  <script>
    //set get has delete clear forEach size
    const m=new Map()
    //使用set添加新成员，键如果已存在，后添加的键值对覆盖已有的
    m.set('age',19).set(true,true).set('age',20);
    m.get('age')
    m.has(true)
    m.delete(1)
    m.delete(true)
    m.forEach((value,key,map)=>{
      console.log(value,key,map);
    })
    m.size
    m.clear()
  </script>
</body>
</html>